Old Metairie Mystery Book Club - The Turn of the Key by Ruth Ware

When Rowan Caine stumbles across the ad, she's looking for something else completely. But it seems like too good an opportunity to miss--a live-in nanny post, with a staggeringly generous salary. And when she arrives at Heatherbrae House, she is smitten--by the luxurious 'smart' home fitted out with all modern conveniences, by the beautiful Scottish Highlands, and by this picture-perfect family. What she doesn't know is that she's stepping into a nightmare--one that will end with a child dead and herself in prison awaiting trial for murder.